1. Field of the Invention
The present invention relates to a method for partially dyeing or tinting a plastic lens and a plastic lens dyed or tinted according to such method.
Recently, plastic lens have been widely been put into practical use because of their light weight properties, high impact resistance, high resistance to fracture, higher workability or the like compared with glass lenses. Plastic lenses have the further advantage that they can easily be dyed and for that reason, they have been dyed with a variety of colors to manufacture lenses having high fashionability.
Moreover, a plastic lens, only a part of which is dyed for the purposes of enhancing its fashionability and commercial merits or the like, has practically been manufactured and used.
2. Related Arts
A conventional method for partially dyeing a plastic lens comprises selectively applying a polymeric compound to only a part of the surface of the plastic lens other than that to be dyed and thus forming a film for masking whereby to prevent the surface from dyeing, dyeing the lens by dipping it in a dyeing bath and then removing the film for masking by, for instance, dissolving it with a dissolving agent. In this respect, reference is made to Laid-Open Japanese Utility Model Appln. Gazett No. 53-24635 (Appln. No. 51-106349).
However, the partially dyed plastic lens manufactured according to the aforementioned method including the use of the masking treatment suffers from the fact that it does not have a commercially acceptable and beautiful boundary between the dyed portion and the nondyed portion and is inadequate in sharpness of the boundary. Moreover, the conventional method for dyeing plastic lenses requires techniques of a high order and expensive which makes the resultant plastic lens more expensive.